CN113365957A

CN113365957A - Ion-exchangeable opaque gahnite-spinel glass-ceramics with high hardness and modulus

Info

Publication number: CN113365957A
Application number: CN201980089951.1A
Authority: CN
Inventors: G·H·比尔; A·L·C·K·A·米切尔; C·M·史密斯
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2018-11-30
Filing date: 2019-11-21
Publication date: 2021-09-07
Anticipated expiration: 2039-11-21
Also published as: US20200172432A1; US20220298063A1; US11370697B2; CN113365957B; JP2022509838A; KR20210099607A; TW202028138A; WO2020112466A1; EP3887327A1

Abstract

Opaque gahnite-spinel glass-ceramics are provided. The glass-ceramic comprises: comprising (Mg)_xZn_1‑x)Al₂O₄Wherein x is less than 1; and ZrO comprising tetragonal crystal form₂、MgTa₂O₆A second crystalline phase of at least one of mullite and cordierite. The glass ceramic has a Young's modulus of 90GPa or more and a hardness of 7.5GPa or more. The glass-ceramic may be ion exchanged. A method for producing the glass-ceramic is also provided.

Description

Ion-exchangeable opaque gahnite-spinel glass-ceramics with high hardness and modulus

This application claims priority from U.S. provisional application serial No. 62/773,682 filed on 30/11/2018, which is hereby incorporated by reference in its entirety.

Background

Technical Field

The present description generally relates to opaque glass-ceramic compositions. More particularly, the present description relates to opaque gahnite-spinel glass ceramics that can form housings for electronic devices.

Technical Field

Portable electronic devices, such as smartphones, tablets, and wearable devices (e.g., watches and fitness trackers), continue to become smaller and more complex. As such, the materials conventionally used on at least one exterior surface of such portable electronic devices continue to become more complex. For example, as portable electronic devices become smaller and thinner to meet consumer demand, the housings for these portable electronic devices also become smaller and thinner, resulting in higher performance requirements for the materials used to form these components.

Therefore, there is a need for materials exhibiting higher performance (e.g., resistance to damage) for use in portable electronic devices.

Disclosure of Invention

According to aspect (1), a glass-ceramic is provided. The glass-ceramic comprises: a first crystal phase comprising (Mg)_xZn_1-x)Al₂O₄Wherein x is less than 1; and a second crystalline phase comprising at least one of: tetragonal ZrO₂、MgTa₂O₆Mullite and cordierite; wherein the glass-ceramic is opaque in the visible light range, has a Young's modulus of 90GPa or more, and has a hardness of 7.5GPa or more.

According to aspect (2), there is provided the glass-ceramic of aspect (1), further comprising Li₂O and Na₂At least one of O.

According to aspect (3), there is provided the glass-ceramic of aspect (1), further comprising Li₂O and Na₂O。

According to aspect (4), there is provided the glass-ceramic of any one of aspects (1) to (3), wherein x is greater than 0.

According to aspect (5), there is provided the glass-ceramic of any one of aspects (1) to (4), further comprising from greater than or equal to 35% by weight to less than or equal to 60% by weight of SiO₂。

According to aspect (6), there is provided the glass-ceramic of any one of aspects (1) to (5), further comprising: 35 to 55 mol% SiO₂(ii) a Greater than or equal to 18 mol% Al₂O₃(ii) a Greater than or equal to 5 mol% MgO; and greater than or equal to 2 mol% P₂O₅。

According to aspect (7), there is provided the glass-ceramic of any one of aspects (1) to (6), further comprising: 0 to 14 mol% ZnO, 0 to 5 mol% TiO ₂0 to 5 mol%Na₂O, 0 to 5 mol% Li₂O, 0 to 2 mol% BaO, 0 to 4 mol% B₂O₃0 to 1 mol% CaO, 0 to 3 mol% Eu₂O₃0 mol% to 6 mol% Ta₂O₅0 mol% to 5 mol% La₂O₃0 mol% to 0.1 mol% As₂O₅And 0 mol% to 0.3 mol% SnO₂。

According to aspect (8), there is provided the glass-ceramic of any one of aspects (1) to (7), wherein ZrO₂+TiO₂+Eu₂O₃+Ta₂O₅+La₂O₃Less than or equal to 6 mol percent.

According to aspect (9), there is provided the glass-ceramic of any one of aspects (1) to (8), wherein the glass-ceramic is substantially free of TiO₂。

According to aspect (10), there is provided the glass-ceramic of any one of aspects (1) to (9), wherein ZrO₂+TiO₂+Eu₂O₃+Ta₂O₅+La₂O₃≦ 5.5 mol%, and the glass-ceramic comprises: la₂O₃、Ta₂O₅And greater than or equal to 2 mol% Li₂At least one of O.

According to the aspect (11), there is provided the glass-ceramic of any one of the aspects (1) to (9), wherein ZrO₂+TiO₂+Eu₂O₃+Ta₂O₅+La₂O₃5.1 mol% or less, and the glass-ceramic contains less than 2 mol% Li₂O and substantially La-free₂O₃And Ta₂O₅。

According to aspect (12), there is provided the glass-ceramic of any one of aspects (1) to (11), wherein the glass-ceramic exhibits a crystallinity of at least about 35 wt.%.

According to aspect (13), there is provided the glass-ceramic of any one of aspects (1) to (12), wherein the glass-ceramic exhibits a crystallinity of from greater than or equal to 35 wt% to less than or equal to 60 wt%.

According to aspect (14), there is provided the glass-ceramic of any one of aspects (1) to (13), wherein the glass-ceramic has a young's modulus of greater than or equal to 100GPa to less than or equal to 125 GPa.

According to aspect (15), there is provided the glass-ceramic of any one of aspects (1) to (14), wherein the glass-ceramic has a hardness of greater than or equal to 8GPa to less than or equal to 13 GPa.

According to aspect (16), there is provided the glass-ceramic of any one of aspects (1) to (15), wherein the glass-ceramic is substantially colorless.

According to the aspect (17), there is provided the glass-ceramic of any one of the aspects (1) to (16), wherein the second crystal phase contains tetragonal ZrO₂。

According to aspect (18), there is provided the glass-ceramic of any one of aspects (1) to (16), wherein the glass-ceramic is substantially free of ZrO₂And the second crystalline phase comprises MgTa₂O₆。

According to aspect (19), there is provided the glass-ceramic of any one of aspects (1) to (16), wherein the glass-ceramic is substantially free of a nucleating agent and the second crystalline phase comprises mullite and cordierite.

According to aspect (20), there is provided the glass-ceramic of any one of aspects (1) to (19), further comprising a compressive stress region extending from a surface of the glass-ceramic to a depth of compression.

According to an aspect (21), a consumer electronics product is provided. The consumer electronic product includes: a housing comprising a front surface, a back surface, and side surfaces; an electronic assembly at least partially within the housing, the electronic assembly including at least a controller, a memory, and a display, the display being located at or adjacent to the front surface of the housing; and a cover substrate disposed over the display, wherein at least a portion of the housing comprises the glass-ceramic of any one of aspects (1) to (19).

According to an aspect (22), a consumer electronics product is provided. The consumer electronic product includes: a housing comprising a front surface, a back surface, and side surfaces; an electronic assembly at least partially within the housing, the electronic assembly including at least a controller, a memory, and a display, the display being located at or adjacent to the front surface of the housing; and a cover substrate disposed over the display, wherein at least a portion of the housing comprises the glass-ceramic of aspect (20).

According to aspect (23), a method is provided. The method comprises the following steps: ceramming the precursor glass to form a glass-ceramic that is opaque in the visible range, wherein the glass-ceramic comprises: a first crystal phase comprising (Mg)_xZn_1-x)Al₂O₄Wherein x is less than 1; and a second crystalline phase comprising at least one of: tetragonal ZrO₂、MgTa₂O₆Mullite and cordierite; wherein the glass-ceramic has a Young's modulus of 90GPa or more, and a hardness of 7.5GPa or more.

According to aspect (24), there is provided the method of aspect (23), further comprising forming nuclei (nuclei) in the precursor glass prior to ceramming.

According to aspect (25), there is provided the method of aspect (24), wherein the forming nuclei comprises heat-treating the precursor glass at a temperature of at least 700 ℃ for a period of at least 1 hour.

According to aspect (26), there is provided the method of any one of aspects (23) to (25), wherein ceramming comprises heat-treating the precursor glass at a temperature of at least 750 ℃ for a period of at least 30 minutes.

According to aspect (27), there is provided the method of aspect (23), wherein the method does not comprise a separate nucleation step.

According to aspect (28), there is provided the method of aspect (23), wherein ceramming comprises irradiating the precursor glass with a laser to form the glass-ceramic.

According to aspect (29), there is provided the method of any one of aspects (23) to (28), further comprising ion-exchanging the glass-ceramic.

According to aspect (30), there is provided the method of aspect (29), wherein the ion exchange comprises contacting the glass-ceramic with a mixed ion exchange bath.

According to the aspect (31),a glass is provided. The glass comprises: 35 to 55 mol% SiO₂Greater than or equal to 18 mol% Al₂O₃Greater than or equal to 5 mol% MgO, greater than or equal to 2 mol% P₂O₅0 to 14 mol% ZnO, 0 to 5 mol% TiO ₂0 mol% to 5 mol% Na₂O, 0 to 5 mol% Li₂O, 0 to 2 mol% BaO, 0 to 4 mol% B₂O₃0 to 1 mol% CaO, 0 to 3 mol% Eu₂O₃0 mol% to 6 mol% Ta₂O₅0 mol% to 5 mol% La₂O₃0 mol% to 0.1 mol% As₂O₅And 0 mol% to 0.3 mol% SnO₂。

Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

Drawings

FIG. 1 schematically shows a cross-section of a glass-ceramic having a compressive stress layer on a surface thereof according to embodiments disclosed and described herein;

FIG. 2A is a plan view of an exemplary electronic device incorporating any of the glass-ceramic articles disclosed herein;

FIG. 2B is a perspective view of the exemplary electronic device of FIG. 2A;

FIG. 3 is a Tunneling Electron Microscope (TEM) image of a glass-ceramic according to an embodiment;

FIG. 4 is a graph of total transmission as a function of wavelength for a comparative example glass sample, a comparative example glass-ceramic sample, and a glass-ceramic according to an embodiment;

FIG. 5 is a photograph of a front view and a side view of a precursor glass that has been partially cerammed by carbon dioxide laser radiation, according to an embodiment.

Detailed Description

Reference will now be made in detail to opaque gahnite-spinel glass-ceramics according to various embodiments. In particular, opaque gahnite-spinel glass ceramics have high hardness and can be ion exchanged. Thus, opaque gahnite-spinel glass ceramics are suitable for use as housings for portable electronic devices.

In the description below, like reference numerals designate similar or corresponding parts throughout the several views shown in the drawings. It is also to be understood that, unless otherwise indicated, terms such as "top," "bottom," "outward," "inward," and the like are words of convenience and are not to be construed as limiting terms. Whenever a group is described as consisting of at least one of a group of elements or a combination thereof, it is understood that the group may consist of any number of those listed elements, either individually or in combination with each other. Unless otherwise indicated, a range of numerical values set forth includes both the upper and lower limits of the range, as well as any range between the stated ranges. As used herein, the indefinite article "a" or "an" and its corresponding definite article "the" mean "at least one" or "one or more", unless otherwise indicated. It is also to be understood that the various features disclosed in the specification and in the drawings may be used in any and all combinations.

Unless otherwise indicated, all components of the glasses and glass-ceramics described herein are expressed in mole percent (mol%), and the compositions are on an oxide basis. All temperatures are expressed in degrees Celsius (. degree. C.) unless otherwise noted.

It is noted that the terms "substantially" and "about" may be used herein to represent the degree of inherent uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms "comprises," "comprising," and any other variation thereof, are intended to cover a non-exclusive inclusion, such that a non-exclusive inclusion does not imply that all of the features and functions of the subject matter claimed herein are in fact, or even wholly, essential to the subject matter. For example, "substantially free of K₂The glass of O' is one in which K is not actively driven₂O is added or dosed to the glass but may be present in very small amounts as a contaminant, for example, in amounts less than about 0.01 mole percent. As used herein, when the term "about" is used to modify a numerical value, the particular numerical value is also disclosed.

The glass-ceramic contains a first crystalline phase, a second crystalline phase, and a residual glass phase. The first crystalline phase may be a predominant crystalline phase, defined herein as the crystalline phase that occupies the largest portion of the glass-ceramic by weight. Thus, the second crystalline phase may be present in less than the weight percent of the first crystalline phase, based on the weight percent of the glass-ceramic. In some embodiments, the glass-ceramic may comprise more than two crystalline phases.

In an embodiment, the first crystalline phase comprises (Mg)_xZn_1-x)Al₂O₄Wherein x is less than 1. Crystalline phase (Mg)_xZn_1-x)Al₂O₄Which may be collectively referred to as a gahnite-spinel solid solution, it is understood that for the case where x is zero, the crystalline phase is pure gahnite. In embodiments, x may be greater than or equal to 0, for example: greater than or equal to about 0.1, greater than or equal to about 0.2, greater than or equal to about 0.3, greater than or equal to about 0.4, greater than or equal to about 0.5, greater than or equal to about 0.6, greater than or equal to about 0.7, greater than or equal to about 0.8, or greater than or equal to about 0.9. In embodiments, x may be less than 1.0, for example: less than or equal to about 0.9, less than or equal to about 0.8, less than or equal to about 0.7, less than or equal to about 0.6, less than or equal to about 0.5, less than or equal to about 0.4, less than or equal to about 0.3, less than or equal to about 0.2, or less than or equal to about 0.1. It should be understood that any of the above ranges may be used in embodimentsIn combination with any other ranges. In embodiments, x may be greater than or equal to 0 to less than 1.0, for example: greater than or equal to about 0.1 to less than or equal to about 0.9, greater than or equal to about 0.2 to less than or equal to about 0.8, greater than or equal to about 0.3 to less than or equal to about 0.7, or greater than or equal to about 0.4 to less than or equal to about 0.6, and all ranges and subranges therebetween.

The crystalline phase has a crystallite size. The opaque nature of glass-ceramics can be attributed at least in part to the large crystallite size. Crystallite size as used herein is determined by powder X-ray diffraction (XRD) analysis, with 5 to 80 degrees 2-theta scanning, unless otherwise specified. The crystallite size was evaluated using the Scherrer formula function from MDI Jade, and the software package was used for phase identification and quantitative analysis.

In embodiments, the second crystalline phase comprises at least one of: tetragonal zirconia (ZrO)₂)、MgTa₂O₆Mullite and cordierite. The presence of the second crystalline phase in the glass-ceramic may depend on the composition of the precursor glass and the ceramming scheme. Formation of tetragonal ZrO in glass ceramics₂Requiring the presence of ZrO in the precursor glass₂. Without wishing to be bound by any particular theory, it is believed that during the ceramming process, tetragonal ZrO₂In a crystal phase of (Mg)_xZn_1-x)Al₂O₄Crystallization occurs before the crystalline phase and functions as (Mg)_xZn_1-x)Al₂O₄The nucleation sites of the crystalline phases. Furthermore, without wishing to be bound by any particular theory, it is believed that any TiO contained in the glass-ceramic₂ZrO partitioned into tetragonal form₂Phase and act as tetragonal ZrO₂The nucleating agent of the phase. The precursor glass contains substantially no or no ZrO₂Then, MgTa₂O₆May be a second crystalline phase. Mullite and cordierite secondary crystal phases may result when the precursor glass is substantially free or free of nucleating agents. In some embodiments, the composition of the precursor glass and the ceramming conditions may result in a glass-ceramic comprising additional crystalline phases beyond those described above.

In embodiments, the total crystallinity of the glass-ceramic is sufficiently high to provide enhanced mechanical properties, such as: hardness, young's modulus and scratch resistance. As used herein, the units of total crystallinity provided are weight%, and refer to the sum of the weight% of all crystalline phases present in the glass-ceramic, relative to the total weight of the glass-ceramic. In embodiments, the total crystallinity is greater than or equal to about 35 weight percent, for example: greater than or equal to about 40 wt%, greater than or equal to about 45 wt%, greater than or equal to about 50 wt%, greater than or equal to about 55 wt%, or greater. In embodiments, the total crystallinity is less than or equal to about 60 weight percent, for example: less than or equal to about 55 wt%, less than or equal to about 50 wt%, less than or equal to about 45 wt%, less than or equal to about 40 wt%, or less. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In embodiments, the total crystallinity of the glass-ceramic is greater than or equal to about 35 wt.% to less than or equal to about 60 wt.%, for example: greater than or equal to about 40 wt% to less than or equal to about 55 wt%, or greater than or equal to about 45 wt% to less than or equal to about 50 wt%, and all ranges and subranges therebetween. The total crystallinity of the glass-ceramic is determined by rietveld quantitative analysis of XRD data acquired as described above. The rietveld analysis models the XRD data using a least squares method and then determines the phase concentration in the sample based on the lattice and scale factors known for the identified phases.

The glass-ceramic is opaque in the visible range. As used herein, a glass-ceramic is considered opaque when exhibiting less than 50% transmission in the visible range (380nm to 760 nm). As used herein, transmittance refers to total transmittance, and is measured by a Perkin Elmer Lambda (Perkin Elmer Lambda)950UV/VIS/NIR spectrophotometer with a 150mm integrating sphere. The sample was mounted to the inlet end of the sphere to allow collection of the wide angle scattered light. Total transmission data was collected with a reference Spectralon reflective disk on the exit end of the ball. The percentage of total transmission (% T) was calculated relative to the open beam baseline measurement. In embodiments, the glass-ceramic exhibits less than 50% transmission in the visible range, for example: less than or equal to about 45%, less than or equal to about 40%, less than or equal to about 35%, less than or equal to about 30%, or less.

In an embodiment, the glass-ceramic appears white. In embodiments, the glass-ceramic may be colorless or substantially colorless. As used herein, substantially colorless refers to the following color coordinate space: l >90, a is-0.2 to 0.2, and b is-0.1 to 0.6. The color coordinates were measured using a UV/Vis/NIR spectrophotometer equipped with an integrating sphere. Measurements were made at wavelengths of 380nm to 770nm with a 2nm spacing with an observer at light sources D65, A and F2 and 10 deg.. The process of determining the color space in the CIE system is described in more detail in "Standard practice for computing the colors of objects by using the CIR System" (ASTM E308-08).

In embodiments, the hardness of the glass-ceramic may be such that the glass-ceramic is less susceptible to breakage, such as by providing increased scratch resistance. Unless otherwise specified, hardness is measured using a nanoindenter, and is reported in units of GPa, as used herein. Nanoindenter measurements were performed using a continuous rigid method with a diamond brookfield tip, as practiced by the Agilent G200 nanoindenter. The continuous stiffness method uses a small sinusoidal displacement signal (1nm amplitude, 45Hz) superimposed on the tip as the tip load enters the specimen surface, and continuously determines the load, depth and contact stiffness. Without wishing to be bound by any particular theory, it is believed that the hardness of the glass-ceramic is due at least in part to the (Mg) contained therein_xZn_1-x)Al₂O₄And a second crystal phase (e.g., tetragonal ZrO)₂) The hardness of (2).

In embodiments, the glass-ceramic has a hardness of greater than or equal to about 7.5GPa, for example: greater than or equal to about 7.6GPa, greater than or equal to about 7.7GPa, greater than or equal to about 7.8GPa, greater than or equal to about 7.9GPa, greater than or equal to about 8.0GPa, greater than or equal to about 8.1GPa, greater than or equal to about 8.2GPa, greater than or equal to about 8.3GPa, greater than or equal to about 8.4GPa, greater than or equal to about 8.5GPa, greater than or equal to about 8.6GPa, greater than or equal to about 8.7GPa, greater than or equal to about 8.8GPa, greater than or equal to about 8.9GPa, greater than or equal to about 9.0GPa, greater than or equal to about 9.1GPa, greater than or equal to about 9.2GPa, greater than or equal to about 9.3GPa, greater than or equal to about 9.4GPa, greater than or equal to about 9.5GPa, greater than or equal to about 9.6GPa, greater than or equal to about 9.7GPa, greater than or equal to about 9.8GPa, greater than or equal to about 9.9.9 GPa, greater than or equal to about 9.9GPa, greater than or equal to about 9.9.9 GPa, greater than or equal to about 10.10 GPa, greater than or equal to about 10.5GPa, greater than or equal to about 10.6GPa, greater than or equal to about 10.7GPa, greater than or equal to about 10.8GPa, greater than or equal to about 10.9GPa, greater than or equal to about 11.0GPa, greater than or equal to about 11.1GPa, greater than or equal to about 11.2GPa, greater than or equal to about 11.3GPa, greater than or equal to about 11.4GPa, greater than or equal to about 11.5GPa, greater than or equal to about 11.6GPa, greater than or equal to about 11.7GPa, greater than or equal to about 11.8GPa, greater than or equal to about 11.9GPa, greater than or equal to about 12.0GPa, greater than or equal to about 12.1GPa, greater than or equal to about 12.2GPa, greater than or equal to about 12.3GPa, greater than or equal to about 12.4GPa, greater than or equal to about 12.5GPa, greater than or equal to about 12.6GPa, greater than or equal to about 12.7GPa, greater than or equal to about 12.8GPa, greater than or equal to about 12.9 GPa. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In embodiments, the glass-ceramic has a hardness of greater than or equal to about 7.5GPa to less than or equal to about 13.0GPa, for example: greater than or equal to about 8.0GPa to less than or equal to about 12.5GPa, greater than or equal to about 8.5GPa to less than or equal to about 12.0GPa, greater than or equal to about 9.0GPa to less than or equal to about 11.5GPa, greater than or equal to about 9.5GPa to less than or equal to about 11.0GPa, greater than or equal to about 10.0GPa to less than or equal to about 10.5GPa, and all ranges and subranges therebetween.

Glass-ceramics according to embodiments may have a young's modulus of greater than or equal to about 90.0GPa, such as: greater than or equal to about 92.0GPa, greater than or equal to about 94.0GPa, greater than or equal to about 96.0GPa, greater than or equal to about 98.0GPa, greater than or equal to about 100.0GPa, greater than or equal to about 102.0GPa, greater than or equal to about 104.0GPa, greater than or equal to about 106.0GPa, greater than or equal to about 108.0GPa, greater than or equal to about 110.0GPa, greater than or equal to about 112.0GPa, greater than or equal to about 114.0GPa, greater than or equal to about 116.0GPa, greater than or equal to about 118.0GPa, greater than or equal to about 120.0GPa, greater than or equal to 122.0GPa, greater than or equal to 124.0GPa, or greater. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In embodiments, the glass-ceramic has a young's modulus of greater than or equal to about 90.0GPa to less than or equal to about 125.0GPa, such as: greater than or equal to about 92.0GPa to less than or equal to about 123.0GPa, greater than or equal to about 94.0GPa to less than or equal to about 121.0GPa, greater than or equal to about 96.0GPa to less than or equal to about 119.0GPa, greater than or equal to about 98.0GPa to less than or equal to about 117.0GPa, greater than or equal to about 100.0GPa to less than or equal to about 115.0GPa, greater than or equal to about 102.0GPa to less than or equal to about 113.0GPa, greater than or equal to about 104.0GPa to less than or equal to about 111.0GPa, greater than or equal to about 106.0GPa to less than or equal to about 109.0GPa, greater than or equal to about 107.0GPa to less than or equal to about 108.0GPa, and all ranges and subranges therebetween. Unless otherwise indicated, the young's modulus values set forth in this disclosure refer to measurements by Resonant ultrasonic Spectroscopy of the general type set forth in ASTM E2001-13 entitled "Standard Guide for ultrasonic testing for Defect Detection in body metal and Non-Metallic Parts" and the units recorded are GPa.

The glass-ceramic may have a strain point and an anneal point that are sufficiently high to allow additional processing of the glass-ceramic at temperatures up to about 800 ℃ without adversely affecting the structural integrity of the glass-ceramic. Such additional processing may include chemical strengthening, such as ion exchange. These elevated processing temperatures may increase the efficiency of the additional processing, for example, reducing the time required for the additional processing. In embodiments, the strain point may be less than or equal to about 900 ℃, such as greater than or equal to about 700 ℃ to less than or equal to about 900 ℃. These strain points enable improved thermal stability and a larger potential temperature range for ion exchange processes. If the strain point is too low, additional processing of the glass-ceramic may be difficult. If the strain point is too high, it may become difficult to manufacture the precursor glass composition.

The composition of the opaque gahnite-spinel glass-ceramic will now be described. In the embodiments of the glass-ceramics described herein, the constituent components (e.g., SiO) are not otherwise specified₂、Al₂O₃、LiO₂And Na₂O, etc.) is based on mole percent (mol%) of the oxide. The components of the glass-ceramic according to embodiments are discussed independently below. It is to be understood that any of the various stated ranges for one component may be combined individually with any of the various stated ranges for any of the other components.

In embodiments of the glass-ceramics disclosed herein, SiO₂Is the largest component. Pure SiO₂Has a low CTE and is alkali free. However, pure SiO₂Has a high melting point. Thus, if SiO is present in the glass-ceramic₂Too high a concentration of (b) may result in a decrease in formability of the precursor glass composition used to form the glass-ceramic due to the higher SiO₂The concentration increases the difficulty of melting the glass, which in turn negatively affects the formability of the precursor glass. In embodiments, the glass composition comprises SiO₂The amount of (a) is generally greater than or equal to about 35.0 mole%, for example: greater than or equal to about 40.0 mole percent, greater than or equal to about 45.0 mole percent, greater than or equal to about 50.0 mole percent, greater than or equal to about 55.0 mole percent, or more. In embodiments, the glass composition comprises SiO₂In an amount less than or equal to about 60.0 mole percent, for example: less than or equal to about 55.0 mole%, less than or equal to about 50.0 mole%, less than or equal to about 45.0 mole%, less than or equal to about 40.0 mole%, or less. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In other embodiments, the glass composition packageContaining SiO₂The amount of (a) is greater than or equal to about 35.0 mol% to less than or equal to 60.0 mol%, for example: greater than or equal to about 35.0 mole% to less than or equal to about 55.0 mole%, greater than or equal to about 40.0 mole% to less than or equal to about 50.0 mole%, about 45.0 mole%, and all ranges and subranges therebetween.

The glass-ceramic of an embodiment may further include Al₂O₃。Al₂O₃The viscosity of a precursor glass composition used to form a glass-ceramic can be increased because it is tetrahedrally coordinated in a glass melt formed from the glass composition when Al is present₂O₃Too high an amount reduces the formability of the glass composition. However, when Al is used₂O₃Concentration of (D) and SiO in the glass composition₂In equilibrium with the concentration of the basic oxide, Al₂O₃The liquidus temperature of the glass melt is reduced, thereby enhancing the liquidus viscosity and improving the compatibility of the glass composition with certain forming processes, such as fusion forming processes. Al in precursor glass₂O₃Also provided is the aluminum necessary to form the gahnite-spinel crystalline phase when the precursor glass is cerammed to form a glass-ceramic. In an embodiment, the glass composition comprises Al₂O₃Is generally greater than or equal to 18.0 mole%, for example: greater than or equal to about 19.0 mole percent, greater than or equal to about 20.0 mole percent, greater than or equal to about 21.0 mole percent, greater than or equal to about 22.0 mole percent, greater than or equal to about 23.0 mole percent, greater than or equal to about 24.0 mole percent, greater than or equal to about 25.0 mole percent, or more. In an embodiment, the glass composition comprises Al₂O₃The amount of (a) is less than or equal to about 26.0 mole%, for example: less than or equal to about 25.0 mole%, less than or equal to about 24.0 mole%, less than or equal to about 23.0 mole%, less than or equal to about 22.0 mole%, less than or equal to about 21.0 mole%, less than or equal to about 20.0 mole%, less than or equal to about 19.0 mole%, or less. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In an embodiment, the glass combinationContaining Al₂O₃The amount of (a) is greater than or equal to about 18.0 mol% to less than or equal to about 26.0 mol%, for example: greater than or equal to about 19.0 mole% to less than or equal to about 25.0 mole%, greater than or equal to about 20.0 mole% to less than or equal to about 24.0 mole%, greater than or equal to about 21.0 mole% to less than or equal to about 23.0 mole%, about 22.0 mole%, and all ranges and subranges between the foregoing values.

The glass-ceramic of an embodiment may further comprise ZnO. The ZnO in the precursor glass provides the zinc necessary for the formation of the gahnite-spinel when the precursor glass is cerammed to form a glass ceramic. In embodiments, the glass composition typically includes ZnO at a concentration of greater than or equal to 0 mol%, for example: greater than or equal to about 1.0 mole%, greater than or equal to about 2.0 mole%, greater than or equal to about 3.0 mole%, greater than or equal to about 4.0 mole%, greater than or equal to about 5.0 mole%, greater than or equal to about 6.0 mole%, greater than or equal to about 7.0 mole%, greater than or equal to about 8.0 mole%, greater than or equal to about 9.0 mole%, greater than or equal to about 10.0 mole%, greater than or equal to about 11.0 mole%, greater than or equal to about 12.0 mole%, greater than or equal to about 13.0 mole%, or more. In embodiments, the glass composition comprises ZnO in an amount of less than or equal to about 15.0 mol%, for example: less than or equal to about 14.0 mole%, less than or equal to about 13.0 mole%, less than or equal to about 12.0 mole%, less than or equal to about 11.0 mole%, less than or equal to about 10.0 mole%, less than or equal to about 9.0 mole%, less than or equal to about 8.0 mole%, less than or equal to about 7.0 mole%, less than or equal to about 6.0 mole%, less than or equal to about 5.0 mole%, less than or equal to about 4.0 mole%, less than or equal to about 3.0 mole%, less than or equal to about 2.0 mole%, less than or equal to about 1.0 mole%, or less. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In embodiments, the glass composition comprises ZnO in an amount of greater than 0 mol% to less than or equal to about 15.0 mol%, for example: greater than or equal to about 1.0 mole% to less than or equal to about 14.0 mole%, greater than or equal to about 2.0 mole% to less than or equal to about 13.0 mole%, greater than or equal to about 3.0 mole% to less than or equal to about 12.0 mole%, greater than or equal to about 4.0 mole% to less than or equal to about 11.0 mole%, greater than or equal to about 5.0 mole% to less than or equal to about 10.0 mole%, greater than or equal to about 6.0 mole% to less than or equal to about 9.0 mole%, greater than or equal to about 7.0 mole% to less than or equal to about 8.0 mole%, and all ranges and subranges therebetween.

The glass-ceramic of an embodiment may further include MgO. The MgO in the precursor glass provides the magnesium necessary to form a crystalline phase containing a spinel solid solution when the precursor glass is cerammed to form a glass-ceramic. In embodiments, the amount of MgO in the glass-ceramic is greater than or equal to about 5.0 mol%, for example: greater than or equal to about 6.0 mole%, greater than or equal to about 7.0 mole%, greater than or equal to about 8.0 mole%, greater than or equal to about 9.0 mole%, greater than or equal to about 10.0 mole%, greater than or equal to about 11.0 mole%, greater than or equal to about 12.0 mole%, greater than or equal to about 13.0 mole%, greater than or equal to about 14.0 mole%, greater than or equal to about 15.0 mole%, or more. In embodiments, the amount of MgO in the glass-ceramic is less than or equal to about 16.0 mol%, for example: less than or equal to about 15.0 mole%, less than or equal to about 14.0 mole%, less than or equal to about 13.0 mole%, less than or equal to about 12.0 mole%, less than or equal to about 11.0 mole%, less than or equal to about 10.0 mole%, less than or equal to about 9.0 mole%, less than or equal to about 8.0 mole%, less than or equal to about 7.0 mole%, less than or equal to about 6.0 mole%, or less. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In embodiments, the amount of MgO in the glass-ceramic is greater than or equal to about 5.0 mol% to less than or equal to about 16.0 mol%, for example: greater than or equal to about 6.0 mol% to less than or equal to about 15.0 mol%, greater than or equal to about 7.0 mol% to less than or equal to about 14.0 mol%, greater than or equal to about 8.0 mol% to less than or equal to about 13.0 mol%, greater than or equal to about 9.0 mol% to less than or equal to about 12.0 mol%, greater than or equal to about 10.0 mol% to less than or equal to about 11.0 mol%, and all ranges and subranges between the foregoing values. In embodiments where the ratio of MgO to ZnO in the glass-ceramic is high, the opacity of the glass-ceramic is enhanced.

The glass-ceramic of embodiments may also include CaO. In embodiments, the amount of CaO in the glass-ceramic is greater than or equal to 0 mol% to less than or equal to about 1.0 mol%, for example: greater than or equal to about 0.1 mole% to less than or equal to 0.9 mole%, greater than or equal to about 0.2 mole% to less than or equal to 0.8 mole%, greater than or equal to about 0.3 mole% to less than or equal to 0.7 mole%, greater than or equal to about 0.4 mole% to less than or equal to 0.6 mole%, about 0.5 mole%, and all ranges and subranges therebetween.

The glass-ceramic may further comprise P₂O₅. Comprising P₂O₅The ion-exchangeable ability of the glass-ceramic can be enhanced. In an embodiment, the glass-ceramic contains P₂O₅The amount of (a) may be greater than or equal to about 2.0 mole%, for example: greater than or equal to about 2.5 mol% P₂O₅Greater than or equal to about 3.0 mole percent, greater than or equal to about 3.5 mole percent, greater than or equal to about 4.0 mole percent, greater than or equal to about 4.5 mole percent, greater than or equal to about 5.0 mole percent, or more. In other embodiments, the glass-ceramic contains P₂O₅The amount of (a) can be greater than or equal to about 2.0 mole% to less than or equal to about 6.0 mole%, for example: greater than or equal to about 2.5 mole% to less than or equal to about 5.5 mole%, greater than or equal to about 3.0 mole% to less than or equal to about 5.0 mole%, greater than or equal to about 3.5 mole% to less than or equal to about 4.5 mole%, about 2.0 mole%, and all ranges and subranges between the foregoing values.

The glass-ceramic of an embodiment may further comprise B₂O₃。B₂O₃The natural damage resistance of the precursor glass can be increased. In other embodiments, the glass composition comprises B₂O₃The amount of (a) is greater than or equal to 0 mole% to less than or equal to about 4.0 mole%, for example: greater than or equal to about 0.5 mol% to less than or equal toAbout 3.5 mole%, greater than or equal to about 1.0 mole% to less than or equal to about 3.0 mole%, greater than or equal to about 1.5 mole% to less than or equal to about 2.5 mole%, about 2.0 mole%, and all ranges and subranges therebetween.

The glass-ceramic of embodiments may further comprise a nucleating agent. The nucleating agent effects the formation of nuclei in the precursor glass used to form the glass-ceramic. In some embodiments, the nucleating agent allows ceramming of the glass-ceramic without a separate nucleation step. The nucleating agent may be selected from ZrO₂、TiO₂、Eu₂O₃、Ta₂O₅And La₂O₃. In embodiments, the total amount of nucleating agent in the glass-ceramic may be greater than or equal to 0 mole percent, for example: greater than or equal to about 1.0 mole%, greater than or equal to about 2.0 mole%, greater than or equal to about 3.0 mole%, greater than or equal to about 4.0 mole%, greater than or equal to about 5.0 mole%, or more. In embodiments, the total amount of nucleating agent in the glass-ceramic may be less than or equal to about 6.0 mole percent, for example: less than or equal to about 5.0 mole%, less than or equal to about 4.0 mole%, less than or equal to about 3.0 mole%, less than or equal to about 2.0 mole%, or less than or equal to about 1.0 mole%, or less. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In embodiments, the total amount of nucleating agent in the glass-ceramic may be greater than or equal to 0 mol% to less than or equal to about 6.0 mol%, such as the following amounts: greater than or equal to about 1.0 mole% to less than or equal to about 5.0 mole%, greater than or equal to about 2.0 mole% to less than or equal to about 4.0 mole%, greater than or equal to about 1.0 mole% to less than or equal to about 3.0 mole%, about 2.0 mole%, and all ranges and subranges between the foregoing values. In some embodiments, the glass-ceramic may contain a nucleating agent in an amount less than or equal to about 5.5 mol%, and additionally contain La₂O₃、Ta₂O₅And greater than or equal to about 2 mol% Li₂At least one of O. In some embodiments, the glass-ceramic contains a nucleating agentCan be less than or equal to about 5.1 mol%, and additionally contains less than 2 mol% Li₂O and substantially La-free₂O₃And Ta₂O₅。

In an embodiment, the glass-ceramic contains Eu₂O₃The amount of (a) may be greater than or equal to 0 mole% to less than or equal to about 3.0 mole%, for example the following amounts: greater than or equal to about 0.5 mole% to less than or equal to about 2.5 mole%, greater than or equal to about 1.0 mole% to less than or equal to about 2.0 mole%, about 1.5 mole%, and all ranges and subranges between the foregoing values.

In an embodiment, the glass-ceramic contains Ta₂O₅The amount of (a) can be greater than or equal to 0 mole% to less than or equal to about 6.0 mole%, for example the following amounts: greater than or equal to about 1.0 mole% to less than or equal to about 5.0 mole%, greater than or equal to about 2.0 mole% to less than or equal to about 4.0 mole%, greater than or equal to about 1.0 mole% to less than or equal to about 3.0 mole%, about 2.0 mole%, and all ranges and subranges between the foregoing values.

In an embodiment, the glass-ceramic contains La₂O₃The amount of (a) can be greater than or equal to 0 mole% to less than or equal to about 5.0 mole%, for example the following amounts: greater than or equal to about 1.0 mole% to less than or equal to about 4.0 mole%, greater than or equal to about 2.0 mole% to less than or equal to about 3.0 mole%, and all ranges and subranges between the foregoing values.

In an embodiment, the glass-ceramic may comprise ZrO₂As the sole nucleating agent. In addition to acting as a nucleating agent, ZrO is present in the precursor glass₂Tetragonal ZrO during the ceramming process₂The crystallization of (4). Using ZrO₂As the sole nucleating agent in the precursor glass composition, the production of a glass-ceramic that is colorless in appearance is achieved. In an embodiment, ZrO in the glass ceramic₂The amount of (b) is greater than 0 mole%, for example: greater than or equal to about 1.0 mole percent, greater than or equal to about 2.0 mole percent, greater than or equal to about 3.0 mole percent, greater than or equal to about 4.0 mole percent, greater than or equal toAbout 5.0 mole%, greater than or equal to about 6.0 mole%, greater than or equal to about 7.0 mole%, greater than or equal to about 8.0 mole%, or greater than or equal to about 9.0 mole%. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In an embodiment, ZrO in the glass ceramic₂The amount of (a) is greater than 0 mole% to less than or equal to about 10.0 mole%, for example: greater than or equal to about 1.0 mole% to less than or equal to about 9.0 mole%, greater than or equal to about 2.0 mole% to less than or equal to about 8.0 mole%, greater than or equal to about 3.0 mole% to less than or equal to about 7.0 mole%, or greater than or equal to about 4.0 mole% to less than or equal to about 6.0 mole%, and all ranges and subranges therebetween.

In embodiments, the glass-ceramic may comprise TiO₂As a nucleating agent. TiO 2₂Is an effective nucleating agent. However, TiO in the precursor glass₂When the amount is too high, the resulting glass-ceramic may have an undesirable colored appearance. Containing TiO₂The glass-ceramic of (a) may have a yellow or brown appearance in the visible range. Without wishing to be bound by any particular theory, it is believed that Ti⁴⁺Reduction to Ti³⁺A colored appearance of the glass-ceramic is produced. In an embodiment, the TiO in the glass-ceramic₂In an amount greater than or equal to 0 mole%, for example: greater than or equal to about 1.0 mole percent, greater than or equal to about 2.0 mole percent, greater than or equal to about 3.0 mole percent, greater than or equal to about 4.0 mole percent, or more. In an embodiment, the TiO in the glass-ceramic₂In an amount less than or equal to about 5.0 mole percent, for example: less than or equal to about 4.0 mole%, less than or equal to about 3.0 mole%, less than or equal to about 2.0 mole%, less than or equal to about 1.0 mole%, or less. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In an embodiment, the TiO in the glass-ceramic₂In an amount of greater than or equal to 0 mole% to less than or equal to about 5.0 mole%, for example: greater than or equal to about 1.0 mol% to less than or equal to about 4.0 mol%, or greater than or equal to about 2.0 mol% to less than or equal to about 3.0 mol%%, and all ranges and subranges between the above values. In embodiments, the glass-ceramic is substantially free or free of TiO₂。

The glass-ceramic may comprise one or more alkali metal oxides. The alkali metal oxide facilitates chemical strengthening of the glass-ceramic, for example, by an ion exchange process. Sum of alkali metal oxides in the glass-ceramic (e.g., Li)₂O、Na₂O and K₂O and other alkali metal oxides, including Cs₂O and Rb₂O) may be referred to as "R₂O', and R₂O may be expressed as mole%. In some embodiments, the glass-ceramic may comprise a mixture of alkali metal oxides, such as: li₂O and Na₂Combination of O, Na₂O and K₂Combination of O, Li₂O and K₂Combinations of O, or Li₂O、Na₂O and K₂A combination of O. In an embodiment, the glass-ceramic contains Li₂O and Na₂At least one of O. The inclusion of the alkali metal oxide mixture in the glass-ceramic may result in a faster and more efficient ion exchange. Without wishing to be bound by any particular theory, it is believed that the alkali metal oxide is segregated into the residual glass phase of the glass-ceramic after ceramming.

The addition of lithium to the glass-ceramic achieves an ion exchange process and further lowers the softening point of the precursor glass composition. In an embodiment, the glass composition comprises Li₂The amount of O is generally greater than or equal to 0 mole%, for example: greater than or equal to about 0.5 mole%, greater than or equal to about 1.0 mole%, greater than or equal to about 1.5 mole%, greater than or equal to about 2.0 mole%, greater than or equal to about 2.5 mole%, greater than or equal to about 3.0 mole%, greater than or equal to about 3.5 mole%, greater than or equal to about 4.0 mole%, greater than or equal to about 4.5 mole%, or more. In some embodiments, the glass composition comprises Li₂The amount of O is less than or equal to about 5.0 mole percent, for example: less than or equal to about 4.5 mole percent, less than or equal to about 4.0 mole percent, less than or equal to about 3.5 mole percent, less than or equal to about 3.0 mole percent, less than or equal to about 2.5 mole%, less than or equal to about 2.0 mole%, less than or equal to about 1.5 mole%, less than or equal to about 1.0 mole%, less than or equal to about 0.5 mole%, or less. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In an embodiment, the glass composition comprises Li₂The amount of O is greater than or equal to 0.0 mole% to less than or equal to about 5.0 mole%, for example: greater than or equal to about 0.5 mole% to less than or equal to about 4.5 mole%, greater than or equal to about 1.0 mole% to less than or equal to 4.0 mole%, greater than or equal to about 1.5 mole% to less than or equal to about 3.5 mole%, greater than or equal to about 2.0 mole% to less than or equal to about 3.0 mole%, about 2.5 mole%, and all ranges and subranges therebetween.

Similar to Li₂O，Na₂O contributes to the ion-exchangeable nature of the glass-ceramic and also lowers the melting point and improves the formability of the precursor glass composition. In an embodiment, the glass composition comprises Na₂The amount of O is generally greater than or equal to 0 mole%, for example: greater than or equal to about 0.5 mole%, greater than or equal to about 1.0 mole%, greater than or equal to about 1.5 mole%, greater than or equal to about 2.0 mole%, greater than or equal to about 2.5 mole%, greater than or equal to about 3.0 mole%, greater than or equal to about 3.5 mole%, greater than or equal to about 4.0 mole%, greater than or equal to about 4.5 mole%, or more. In some embodiments, the glass composition comprises Na₂The amount of O is less than or equal to about 5.0 mole percent, for example: less than or equal to about 4.5 mole%, less than or equal to about 4.0 mole%, less than or equal to about 3.5 mole%, less than or equal to about 3.0 mole%, less than or equal to about 2.5 mole%, less than or equal to about 2.0 mole%, less than or equal to about 1.5 mole%, less than or equal to about 1.0 mole%, less than or equal to about 0.5 mole%, or less. It should be understood that any of the above ranges may be combined with any other ranges in an embodiment. In an embodiment, the glass composition comprises Na₂The amount of O is greater than or equal to 0.0 molar% to less than or equal to about 5.0 molar%, for example: is greater thanOr equal to about 0.5 mole% to less than or equal to about 4.5 mole%, greater than or equal to about 1.0 mole% to less than or equal to 4.0 mole%, greater than or equal to about 1.5 mole% to less than or equal to about 3.5 mole%, greater than or equal to about 2.0 mole% to less than or equal to about 3.0 mole%, about 2.5 mole%, and all ranges and subranges therebetween.

In embodiments, the glass-ceramic may additionally comprise BaO. The inclusion of BaO in the glass-ceramic increases the refractive index of the residual glass phase in the glass-ceramic. BaO can be added to the glass melt as both carbonate and nitrate to maintain the oxidation state of the system during melting, preventing when TiO is used₂When present in the composition, Ti⁴⁺Reduction to Ti³⁺. BaO may act to prevent the formation of TiO₂Resulting in undesirable color effects of the glass-ceramic. In embodiments, the glass-ceramic may contain BaO in an amount of greater than or equal to 0 mol% to less than or equal to about 2.0 mol%, for example: greater than or equal to about 0.5 mole% to less than or equal to about 1.5 mole%, about 1.0 mole%, and all ranges and subranges therebetween.

In embodiments, the glass-ceramic may optionally include one or more fining agents. In some embodiments, the fining agent may include, for example, tin oxide (SnO)₂) And/or arsenic oxide. In embodiments, SnO present in the glass composition₂The amount of (c) may be less than or equal to 0.3 mole%, for example: greater than or equal to 0 mole% to less than or equal to 0.3 mole%, greater than or equal to 0.1 mole% to less than or equal to 0.2 mole%, and all ranges and subranges between the foregoing values. In embodiments, the amount of arsenic oxide present in the glass-ceramic can be greater than or equal to 0 mole% to less than or equal to 0.1 mole%, and all ranges and subranges between the above values. In embodiments, the arsenic oxide may also function as a bleaching agent. In embodiments, the glass-ceramic may be free or substantially free of one or both of arsenic and antimony.

As described above, glass-ceramics according to embodiments may be formed from precursor glass articles by any suitable method, such as: slit forming, float forming, roll forming, fusion forming, and the like.

The precursor glass article can be characterized by the manner in which it is formed. For example, the precursor glass article can be characterized as float formable (i.e., formed by a float process), down drawable, specifically, fusion formable, or slot drawable (i.e., formed by a down draw process such as a fusion draw process or a slot draw process).

Some embodiments of the precursor glass articles described herein may be formed by a downdraw process. The downdraw process produces glass articles having a uniform thickness with a relatively pristine surface. Because the average flexural strength of the glass article is controlled by the amount and size of the surface flaws, the pristine surface that is minimally contacted has a higher initial strength. In addition, the drawn glass article has a very flat, smooth surface that can be used for end applications without costly grinding and polishing.

Some embodiments of the precursor glass article may be described as being fusion-formable (i.e., formable using a fusion-draw process). The fusion process uses a draw tank having a channel for receiving molten glass feedstock. The channel has weirs that open at the top of both sides of the channel along the length of the channel. As the channel is filled with molten material, the molten glass overflows the weir. Under the influence of gravity, the molten glass flows down from the outer surface of the draw tank as two flowing glass films. The outer surfaces of these drawn cans extend downwardly and inwardly so that they join at the edge below the drawn can. The two flowing glass films are joined at the edge to fuse and form a single flowing glass article. The fusion drawing method has the advantages that: since the two glass films overflowing the channel fuse together, neither outer surface of the resulting glass article is in contact with any part of the apparatus. Thus, the surface properties of the fusion drawn glass article are not affected by such contact.

Some embodiments of the precursor glass articles described herein may be formed by a slot draw process. The slot draw process is different from the fusion draw process. In the slot draw process, molten raw material glass is supplied to a draw tank. The bottom of the drawn can has an open slot with a nozzle extending along the length of the slot. The molten glass flows through the slot/nozzle and is drawn down as a continuous glass article and into an annealing zone.

The glass-ceramic may be formed by ceramming a precursor glass under any suitable conditions. The ceramming does not necessarily involve a separate nucleation process for the purpose of forming crystal nuclei in the precursor glass. The ability to produce transparent glass-ceramics without a separate nucleation step reduces the complexity of the production process and results in energy and time savings. In some embodiments, inclusion of a nucleation treatment may enable additional control over the size of the crystallites produced.

In embodiments, ceramming occurs at a temperature of greater than or equal to about 750 ℃, for example: greater than or equal to about 800 ℃, greater than or equal to about 850 ℃, greater than or equal to about 900 ℃, greater than or equal to about 950 ℃, greater than or equal to about 1000 ℃, greater than or equal to about 1050 ℃, greater than or equal to about 1100 ℃, or higher. In embodiments, ceramming occurs at a temperature of greater than or equal to about 750 ℃ to less than or equal to about 1100 ℃, for example: greater than or equal to about 800 ℃ to less than or equal to about 1050 ℃, greater than or equal to about 850 ℃ to less than or equal to about 1000 ℃, or greater than or equal to about 900 ℃ to less than or equal to about 950 ℃, and all ranges and subranges therebetween.

In embodiments, ceramming continues for a period of time greater than or equal to about 30 minutes, such as: greater than or equal to about 1.0 hour, greater than or equal to about 1.5 hours, greater than or equal to about 2.0 hours, greater than or equal to about 2.5 hours, greater than or equal to about 3.0 hours, greater than or equal to about 3.5 hours, greater than or equal to about 4.0 hours, greater than or equal to about 4.5 hours, greater than or equal to about 5.0 hours, greater than or equal to about 5.5 hours, greater than or equal to about 6.0 hours, greater than or equal to about 6.5 hours, greater than or equal to about 7.0 hours, greater than or equal to about 7.5 hours, greater than or equal to about 8.0 hours, greater than or equal to about 8.5 hours, greater than or equal to about 9.0 hours, greater than or equal to about 9.5 hours, greater than or equal to about 10.0 hours, greater than or equal to about 10.5 hours, greater than or equal to about 11.0 hours, greater than or equal to about 11.5 hours, greater than or equal to about 12.0 hours, greater than or equal to about 12.5 hours, greater than or equal to about 13.0 hours, greater than or equal to about 14.0 hours, greater than or equal to about 14.5 hours, greater than or equal to about 15.0 hours, greater than or equal to about 15.5 hours, greater than or equal to about 16.0 hours, greater than or equal to about 16.5 hours, greater than or equal to about 17.0 hours, greater than or equal to about 17.5 hours, greater than or equal to about 18.0 hours, greater than or equal to about 18.5 hours, greater than or equal to about 19.0 hours, greater than or equal to about 19.5 hours, greater than or equal to about 20.0 hours, greater than or equal to about 20.5 hours, greater than or equal to about 21.0 hours, greater than or equal to about 21.5 hours, greater than or equal to about 22.0 hours, greater than or equal to about 22.5 hours, greater than or equal to about 23.0 hours, or greater than or equal to about 23.5 hours. In embodiments, ceramming lasts for a period of time greater than or equal to about 30 minutes to less than or equal to about 24.0 hours, such as: greater than or equal to about 1.0 hour to less than or equal to about 23.0 hours, greater than or equal to about 1.5 hours to less than or equal to about 22.0 hours, greater than or equal to about 2.0 hours to less than or equal to about 21.0 hours, greater than or equal to about 2.5 hours to less than or equal to about 20.0 hours, greater than or equal to about 3.0 hours to less than or equal to about 19.0 hours, greater than or equal to about 3.5 hours to less than or equal to about 18.0 hours, greater than or equal to about 4.0 hours to less than or equal to about 17.0 hours, greater than or equal to about 4.5 hours to less than or equal to about 16.0 hours, greater than or equal to about 5.0 hours to less than or equal to about 15.0 hours, greater than or equal to about 5.5 hours to less than or equal to about 14.0 hours, greater than or equal to about 6.0 hours to less than or equal to about 13.0 hours, greater than or equal to about 6.5 hours to less than or equal to about 12.0 hours, greater than or equal to about 7.0 hours to about 11.0 hours, greater than or equal to about 7.5 hours to less than or equal to about 10.0 hours, or greater than or equal to about 8.0 hours to less than or equal to about 9.0 hours, and all ranges and subranges therebetween.

In embodiments containing a separate nucleation treatment, the nucleation treatment occurs at a temperature greater than or equal to about 700 ℃, for example: greater than or equal to about 750 ℃, greater than or equal to about 800 ℃, greater than or equal to about 850 ℃, greater than or equal to about 900 ℃, greater than or equal to about 950 ℃, or greater than or equal to about 1000 ℃, or higher. In embodiments, the nucleation occurs at a temperature of greater than or equal to about 700 ℃ to less than or equal to about 1000 ℃, for example: greater than or equal to about 750 ℃ to less than or equal to about 950 ℃, or greater than or equal to about 800 ℃ to less than or equal to about 900 ℃, and all ranges and subranges therebetween.

In embodiments, the nucleation treatment extends over a period of time greater than 0 minutes, such as: greater than or equal to about 30 minutes, greater than or equal to about 1.0 hour, greater than or equal to about 1.5 hours, greater than or equal to about 2.0 hours, greater than or equal to about 2.5 hours, greater than or equal to about 3.0 hours, greater than or equal to about 3.5 hours, greater than or equal to about 4.0 hours, or longer. In embodiments, ceramming lasts for a period of time greater than or equal to about 30 minutes to less than or equal to about 4.0 hours, such as: greater than or equal to about 1.0 hour to less than or equal to about 3.5 hours, or greater than or equal to about 1.5 hours to less than or equal to about 3.0 hours, as well as all ranges and subranges therebetween.

In an embodiment, ceramming may be performed by irradiating the precursor glass with a laser. Localized ceramming of regions or portions of the precursor glass article is achieved using a laser, and such localized ceramming can create residual stresses and strains in the glass-ceramic. The stress and strain may then create areas of the glass-ceramic article with increased mechanical strength, such as the edges of the housing or back plate for a mobile electronic device. In an embodiment, the laser used for the ceramming process may be a carbon dioxide laser. Furthermore, the use of a laser in the ceramming process enables the formation of a pattern of ceramic regions in the glass-ceramic.

In embodiments, the glass-ceramic is also chemically strengthened, such as by ion exchange, to produce a glass-ceramic that is resistant to damage, such as, but not limited to, display overlay applications. Referring to fig. 1, the glass-ceramic has a first region (e.g., the first and second

compressive layers

120, 122 in fig. 1) that is under compressive stress, which extends from the surface to a depth of compression (DOC) of the glass-ceramic, and a second region (e.g., the central region 130 in fig. 1) that is under tensile stress or Central Tension (CT), which extends from the DOC into a central or interior region of the glass-ceramic. As used herein, DOC refers to the depth at which the stress within the glass-ceramic changes from compression to tension. At the DOC, the stress transitions from positive (compressive) stress to negative (tensile) stress, thus exhibiting a zero stress value.

According to the usual practice in the art, compressive or compression stress is expressed as negative stress: (<0) And tensile or stretching stress is expressed as normal stress: (>0). However, throughout this specification, CS is expressed as a positive value or an absolute value, i.e., CS ═ CS |, as set forth herein. The Compressive Stress (CS) may have a maximum at the glass surface, and CS may vary as a function of the distance d from the surface. Referring again to FIG. 1, the first compressive layer 120 extends from the first surface 110 to a depth d₁And a second compressive layer 122 extends from the second surface 112 to a depth d₂. Together, these sections define the compression or CS of the glass-ceramic 100. Compressive stress (including surface CS) was measured by a surface stress meter (FSM) using a commercial instrument such as FSM-6000 manufactured by Orihara Industrial co. Surface stress measurement relies on the accurate measurement of the Stress Optical Coefficient (SOC), which is related to the birefringence of the glass. The SOC was then measured according to protocol C (Method of Glass disks) described in ASTM Standard C770-16, entitled "Standard Test Method for measuring Glass Stress-Optical Coefficient", which is incorporated herein by reference in its entirety.

The compressive stresses of both compressive stress regions (120, 122 in fig. 1) are balanced by the tension stored in the central region (130) of the glass. The maximum Central Tension (CT) and DOC values were measured using the scattered light polarizer (SCALP) technique known in the art.

Compressive stress can be created in the glass by exposing the glass to an ion exchange solutionAnd (3) a layer. In an embodiment, the ion exchange solution may be a molten nitrate salt. In some embodiments, the ion exchange solution may be molten KNO₃Molten NaNO₃Or a combination thereof. In certain embodiments, the ion exchange solution may comprise less than or equal to about 100% molten KNO₃For example: less than or equal to about 95% molten KNO₃Less than or equal to about 90% molten KNO₃Less than or equal to about 80% melting KNO₃Less than or equal to about 75% molten KNO₃Less than or equal to about 70% molten KNO₃Less than or equal to about 65% molten KNO₃Less than or equal to about 60% molten KNO₃Or less. In certain embodiments, the ion exchange solution can comprise greater than or equal to about 10% molten NaNO₃For example: greater than or equal to about 15% molten NaNO₃Greater than or equal to about 20% molten NaNO₃Greater than or equal to about 25% molten NaNO₃Greater than or equal to about 30% molten NaNO₃Greater than or equal to about 35% molten NaNO₃Greater than or equal to about 40% molten NaNO₃Or more. In other embodiments, the ion exchange solution may comprise: about 80% melting KNO₃And about 20% molten NaNO₃About 75% melting KNO₃And about 25% molten NaNO₃About 70% melting KNO₃And about 30% molten NaNO₃About 65% melting KNO₃And about 35% molten NaNO₃Or about 60% melting KNO₃And about 40% molten NaNO₃And all ranges and subranges between the above values. In embodiments, other sodium and potassium salts may be used in the ion exchange solution, for example, sodium or potassium nitrite, sodium or potassium phosphate, or sodium or potassium sulfate. In embodiments, the ion exchange solution may comprise silicic acid, for example less than or equal to about 1 wt% silicic acid.

The glass-ceramic may be exposed to the ion exchange solution by immersing the glass-ceramic in a bath of the ion exchange solution, spraying the ion exchange solution onto the glass-ceramic, or any other means of physically applying the ion exchange solution to the glass-ceramic. According to embodiments, the temperature of the ion exchange solution after exposure to the glass-ceramic may be greater than or equal to 400 ℃ to less than or equal to 500 ℃, for example: greater than or equal to 410 ℃ to less than or equal to 490 ℃, greater than or equal to 420 ℃ to less than or equal to 480 ℃, greater than or equal to 430 ℃ to less than or equal to 470 ℃, or greater than or equal to 440 ℃ to less than or equal to 460 ℃, and all ranges and subranges between the foregoing values. In embodiments, the glass-ceramic may be exposed to the ion exchange solution for a duration of greater than or equal to 4 hours to less than or equal to 48 hours, for example: greater than or equal to 8 hours to less than or equal to 44 hours, greater than or equal to 12 hours to less than or equal to 40 hours, greater than or equal to 16 hours to less than or equal to 36 hours, greater than or equal to 20 hours to less than or equal to 32 hours, or greater than or equal to 24 hours to less than or equal to 28 hours, as well as all ranges and subranges between the foregoing values.

The ion exchange process may be carried out in an ion exchange solution under processing conditions that provide the disclosed improved compressive stress profile, such as U.S. patent application publication No. 2016/0102011, which is incorporated herein by reference in its entirety.

After the ion exchange process is performed, it is understood that the composition at the surface of the glass-ceramic may differ from the composition of the glass-ceramic as it is formed (i.e., the glass-ceramic prior to being subjected to the ion exchange process). This results from one type of alkali metal ion in the as-formed glass (e.g., Li)⁺Or Na⁺) Are respectively coated with larger alkali metal ions (e.g. Na)⁺Or K⁺) And (4) replacing. However, in embodiments, the composition of the glass-ceramic at or near the depth center of the glass article will be subject to at least the ion exchange process and may have substantially the same or the same composition as the glass-ceramic as it was formed.

The glass-ceramic articles disclosed herein can be integrated into another article, such as an article (or display article) having a display screen (e.g., consumer electronics, including mobile phones, tablets, computers, navigation systems, and the like), a construction article, a transportation article (e.g., vehicles, trains, aircraft, navigation systems, and the like), an electrical article, or any article requiring partial transparency, scratch resistance, abrasion resistance, or a combination thereof. An exemplary article incorporating any of the glass-ceramic articles disclosed herein is shown in fig. 2A and 2B. Specifically, FIGS. 2A and 2B show a consumer electronic device 200 comprising: a housing 202 having a front surface 204, a back surface 206, and side surfaces 208; electronic components (not shown) at least partially located or entirely within the housing and including at least a controller, a memory, and a display 210 located at or adjacent to the front surface of the housing; and a cover substrate 212 positioned at or above the front surface of the housing so that it is positioned over the display. In some embodiments, at least a portion of at least one of the cover substrate 212 and/or the housing 202 can include any of the glass articles disclosed herein.

Examples

The embodiments are further clarified by the following examples. It is to be understood that these examples are not intended to limit the embodiments described above.

Precursor glasses having the compositions in table 1 below were prepared. In table 1, all components are in mole percent and various properties of the glass compositions were measured according to the methods described herein.

TABLE 1

TABLE 1 (continuation)

Analysis (mol%)	7	8	9	10	11	12
							SiO₂	47.8	46.1	44.5	54.1	54.1	54.1
Al₂O₃	23.8	24.7	25.6	20.8	20.6	21.3
							ZnO	12.7	13.2	13.7	10.5	10.4	10.3
MgO	7.1	7.4	7.7	6.0	6.0	5.8
							ZrO₂	2.2	2.3	2.2	2.3	2.4	3.2
TiO₂	2.2	2.2	2.2	2.2	2.2	0.0
							Li₂O
Na₂O	2.7	2.7	2.7	2.6	2.6	3.7
							BaO	1.2	1.2	1.2	1.2	1.2	1.2
As₂O₅	0.1	0.1	0.1	0.1	0.1	0.1
							NO₂	0.2	0.2	0.2	0.2	0.2	0.2
B₂O₃
							CaO
Eu₂O₃
							Ta₂O₅
La₂O₃
							P₂O₅
Density (g/cm)³)	2.957	2.98	3.006	2.856	2.858	0
							Hardness (GPa)				8.36	8.30
Poisson ratio				0.257	0.252
							Shear modulus (GPa)				39.0	39.0
Young's modulus (GPa)				97.9	97.6
							RI@589.3nm				1.5830	1.5840

TABLE 1 (continuation)

Analysis (mol%)	13	14	15	16	17	18
							SiO₂	54.9	47.7	44.1	49.7	54.3	52.7
Al₂O₃	20.7	23.6	25.4	19.7	20.5	19.7
							ZnO	10.4	12.5	13.6	9.6		10.1
MgO	6.0	7.0	7.7	5.4	15.9	5.6
							ZrO₂	2.9	2.8	2.9	4.3	3.0	3.2
TiO₂	2.2	2.2	2.2		2.2	2.2
							Li₂O
Na₂O	2.7	2.7	2.6	3.6	2.6	2.5
							BaO	0.0	1.2	1.2	1.1	1.2	1.2
As₂O₅	0.1	0.1	0.1	0.1	0.1	0.1
							NO₂		0.2	0.2	0.2	0.2	0.2
B₂O₃				3.9
							CaO
Eu₂O₃
							Ta₂O₅
La₂O₃						2.5
							P₂O₅				2.2
Density (g/cm)³)	2.829	2.967	3.016		2.726	0
							Hardness (GPa)
Poisson ratio
							Shear modulus (GPa)
Young's modulus (GPa)
							RI@589.3nm	1.5832	1.6026	1.6117		1.5745

TABLE 1 (continuation)

The density value refers to a value measured by the buoyancy method according to ASTM C693-93 (2013). Hardness was measured using a nanoindenter, as described above. Young's modulus and shear modulus were measured by a resonance Ultrasound Spectroscopy technique of the general type set forth in ASTM E2001-13, entitled "Standard Guide for resonance ultrasonic Spectroscopy for Defect Detection in Box Metallic and Non-Metallic Parts". The Refractive Index (RI) of the precursor glass was measured at a wavelength of 589.3 nm.

TABLE 2

Table 2 provides a ceramming protocol for forming glass-ceramics from the precursor glass compositions. Unless otherwise stated, the ceramization protocol includes: the precursor glass was heated from room temperature to the indicated processing conditions in the furnace at a ramp rate of 5 ℃/minute for the indicated time, and then the furnace was allowed to cool to ambient temperature. The ceramming protocol, indicating the slow temperature rise 1 condition, includes: the precursor glass was heated in a furnace from room temperature to 700 c at a ramp rate of 5 c/min and then at a ramp rate of 1 c/min to the processing conditions shown.

The phase set of the glass-ceramic formed by ceramming of the precursor glass composition was determined based on X-ray diffraction (XRD) analysis and is reported in table 4 below. Measurement of residual glass, gahnite and tetragonal ZrO present in glass-ceramics by Rittwold quantitative analysis₂The amount of phases is in weight%. The phases detected in the phase set determination are described in table 3 below.

TABLE 3

Glass-ceramics were produced from the compositions of table 1 using the ceramization protocol of table 2. Table 4 below reports the properties of the resulting glass-ceramic and the ceramming protocol that resulted in the glass-ceramic. In addition, as noted in table 4, some glass-ceramics were ion exchanged. The density differences reported in table 5 refer to the change in density of the precursor glass when the glass-ceramic is formed.

TABLE 4

Table 4 (continuation)

Table 4 (continuation)

Table 4 (continuation)

Table 4 (continuation)

Table 4 (continuation)

Table 4 (continuation)

Table 4 (continuation)

Table 4 (continuation)

The crystallite size reported is in angstroms. For the case where the crystallite size is denoted by "-", the crystallite size of the relevant phase is not determined.

Fig. 3 is a Tunnel Electron Microscope (TEM) image of glass composition 5 after ceramization at 1000 ℃ for 4 hours. FIG. 3 shows the darkest regions corresponding to the residual glass phase, the gray regions corresponding to the gahnite-spinel solid solution crystal phase and the brightest regions corresponding to the titanium-containing tetragonal ZrO₂A crystalline phase. As shown in fig. 3, the crystalline phase forms a dendritic structure.

FIG. 4 provides the total transmission measured over the visible wavelength range for a comparative example transparent glass sample, a comparative example transparent glass ceramic sample, and a glass ceramic formed by ceramming of glass composition 2. Each sample was 1mm thick.

FIG. 5 is a photograph of a front view and a side view of a precursor glass that has been partially cerammed by carbon dioxide laser radiation, according to an embodiment. The transparent region is residual glass, and the opaque region contains a crystalline phase.

All compositional components, relationships, and proportions provided in this specification are in mole% unless otherwise specified. All ranges disclosed in this specification are to be understood to encompass any and all ranges and subranges subsumed by the broadly disclosed range, whether or not explicitly stated before or after the disclosed range.

It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the present description cover the modifications and variations of the various embodiments described herein provided they come within the scope of the appended claims and their equivalents.

Claims

1. A glass-ceramic, comprising:

comprises (Mg)_xZn_1-x)Al₂O₄Wherein x is less than 1; and

a second crystalline phase comprising at least one of: tetragonal ZrO₂、MgTa₂O₆Mullite and cordierite;

wherein the glass ceramic is opaque in a visible light range, has a Young's modulus of 90GPa or more and a hardness of 7.5GPa or more.

2. The glass-ceramic of claim 1 further comprising Li₂O and Na₂At least one of O.

3. The glass-ceramic of claim 1 further comprising Li₂O and Na₂O。

4. The glass ceramic of any one of claims 1 to 3, wherein x is greater than 0.

5. The glass-ceramic of any one of claims 1-4, further comprising greater than or equal to 35 mol% to less than or equal to 60 mol% SiO₂。

6. The glass-ceramic of any one of claims 1 to 5, further comprising:

35 to 55 mol% SiO₂；

Greater than or equal to 18 mol% Al₂O₃；

Greater than or equal to 5 mol% MgO; and

greater than or equal to 2 mol% P₂O₅。

7. The glass-ceramic of claim 6, further comprising:

0 to 14 mol% ZnO;

0 moleMol% to 5 mol% TiO₂；

0 mol% to 5 mol% Na₂O；

0 mol% to 5 mol% Li₂O；

0 to 2 mol% BaO;

0 to 4 mol% B₂O₃；

0 to 1 mol% CaO;

0 to 3 mol% Eu₂O₃；

0 to 6 mol% Ta₂O₅；

0 mol% to 5 mol% La₂O₃；

0 mol% to 0.1 mol% As₂O₅(ii) a And

0 to 0.3 mol% SnO₂。

8. The glass ceramic according to any of claims 1 to 7, wherein ZrO₂+TiO₂+Eu₂O₃+Ta₂O₅+La₂O₃Less than or equal to 6 mol percent.

9. The glass-ceramic of any one of claims 1 to 8, wherein the glass-ceramic is substantially free of TiO₂。

10. The glass ceramic according to any of claims 1 to 9, wherein ZrO₂+TiO₂+Eu₂O₃+Ta₂O₅+La₂O₃≦ 5.5 mol%, and the glass-ceramic comprises at least one of:

La₂O₃；

Ta₂O₅(ii) a And

greater than or equal to 2 mol% Li₂O。

11. The glass ceramic according to any of claims 1 to 10, wherein ZrO₂+TiO₂+Eu₂O₃+Ta₂O₅+La₂O₃5.1 mol% or less, and the glass-ceramic contains less than 2 mol% Li₂O and substantially La-free₂O₃And Ta₂O₅。

12. The glass-ceramic of any one of claims 1 through 11, wherein the glass-ceramic exhibits a crystallinity of at least 35 wt.%.

13. The glass-ceramic of any one of claims 1 to 12, wherein the glass-ceramic exhibits a crystallinity of from greater than or equal to 35 wt.% to less than or equal to 60 wt.%.

14. The glass ceramic of any one of claims 1 through 13, wherein the glass ceramic has a young's modulus of greater than or equal to 100GPa to less than or equal to 125 GPa.

15. The glass ceramic of any one of claims 1 through 14, wherein the glass ceramic has a hardness of greater than or equal to 8GPa to less than or equal to 13 GPa.

16. The glass-ceramic of any one of claims 1 to 15, wherein the glass-ceramic is substantially colorless.

17. The glass ceramic of any of claims 1 through 16, wherein the second crystalline phase comprises tetragonal ZrO₂。

18. The glass-ceramic of any one of claims 1 to 17, wherein the glass-ceramic is substantially free of ZrO₂And the second crystalline phase comprises MgTa₂O₆。

19. The glass-ceramic of any one of claims 1 to 18, wherein the glass-ceramic is substantially free of a nucleating agent and the second crystalline phase comprises mullite and cordierite.

20. The glass ceramic of any one of claims 1 to 19, further comprising a compressive stress region extending from a surface of the glass ceramic to a depth of compression.

21. A consumer electronic product, comprising:

a housing comprising a front surface, a back surface, and side surfaces;

an electronic assembly at least partially located within the housing, the electronic assembly including at least a controller, a memory, and a display, the display located at or adjacent to a front surface of the housing; and

a cover substrate disposed over the display,

wherein at least a portion of the housing comprises the glass-ceramic of any one of claims 1-19.

22. A consumer electronic product, comprising:

a housing comprising a front surface, a back surface, and side surfaces;

a cover substrate disposed over the display,

wherein at least a portion of the housing comprises the glass-ceramic of claim 20.

23. A method, comprising:

ceramming the precursor glass to form a glass-ceramic that is opaque in the visible range,

wherein the glass-ceramic comprises:

comprises (Mg)_xZn_1-x)Al₂O₄Wherein x is less than 1; and

a second crystal phase comprisingAt least one of: tetragonal ZrO₂、MgTa₂O₆Mullite and cordierite;

wherein the glass ceramic has a Young's modulus of 90GPa or more and a hardness of 7.5GPa or more.

24. The method of claim 23, further comprising forming nuclei in the precursor glass prior to ceramming.

25. The method of claim 24, wherein nucleating comprises heat treating the precursor glass at a temperature of at least 700 ℃ for a period of at least 1 hour.

26. The method of claim 23, wherein ceramming comprises heat treating the precursor glass at a temperature of at least 750 ℃ for a period of at least 30 minutes.

27. The method of claim 23 or 26, wherein the method does not comprise a separate nucleation step.

28. The method of any one of claims 23 to 27, wherein ceramming comprises irradiating a precursor glass with a laser to form a glass-ceramic.

29. The method of any one of claims 23 to 28, further comprising ion exchanging the glass-ceramic.

30. The method of claim 29, wherein ion exchanging comprises contacting the glass-ceramic with a mixed ion exchange bath.

31. A glass, comprising:

35 to 55 mol% SiO₂；

Greater than or equal to 18 mol% Al₂O₃；

Greater than or equal to 5 mol% MgO;

greater than or equal to 2 mol% P₂O₅；

0 to 14 mol% ZnO;

0 to 5 mol% TiO₂；

0 mol% to 5 mol% Na₂O；

0 mol% to 5 mol% Li₂O；

0 to 2 mol% BaO;

0 to 4 mol% B₂O₃；

0 to 1 mol% CaO;

0 to 3 mol% Eu₂O₃；

0 to 6 mol% Ta₂O₅；

0 mol% to 5 mol% La₂O₃；

0 mol% to 0.1 mol% As₂O₅(ii) a And

0 to 0.3 mol% SnO₂。